Dam failure a quake risk for Campbell River

Officials in Campbell River areurging residents to prepare for massiveflooding when the 'Big One' hits.

While many areas on the coastriskinundation from the sea, thedanger in Campbell River will come from inland,where there are two large dams to the west of the city.

"It is predicted by BC Hydro that our old dams will not survive a catastrophic earthquake,"ShaunKoopman,the protective services coordinator for Strathcona Regional District, said in an interview with On the Island's Gregor Craigie.

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If boththe earth-filled StrathconaDamandJohn Hart Dambreachin a quake, Koopman said,"we would expect about four to six metres of water to flood large areas along the Campbell River, going into our downtown core within half an hour to 40 minutes."

The fast-moving water would devastate Campbell River's downtown area.

"It has the ability to wipe things away and take debris with it," Koopman said,"compromising both our firehall and ferry terminal, along with local businesses andtourist areas."

"We have a beautiful ocean walk and that would bea major area affected," he said.

For residents and tourists in the area in an earthquake, Koopman said, "the shaking is their warning."

"Once the shaking starts, try to get as far away from the river asyou possibly can if you're in the inundation zone."

Dam breach a worst-case scenario

BC Hydro spokesman Stephen Watson said whileit isimportant to prepare for the worst-case scenario, a dam failure is a possibility, not a certainty.

He said officials can reducethe pressure on the John Hart Dam after an earthquake by releasing water toquickly lower the reservoir10 metres without flooding the city.

That's not an option for the larger Strathcona Dam reservoir, Watson said.

However, Hydro hasplans to reduce the earthquake risk for boththe John Hart Dam and the Strathcona Dam at a cost of hundreds of millions of dollars.

Seismic improvements to start in 2020

The John Hart Dam Seismic Upgrade Project still needs final design andregulatory approval. Watson said that work is expected to begin around 2020.

Hesaid StrathconaDam Low Level OutletProject is expected to begin around the same time.

Theproject would construct an underground tunnel that wouldallow the release of water downstream to relieve pressure from the StrathconaDam.

Campbell River is not the only Vancouver Island where BC Hydro identified an older earth-filled dam as a risk for failure and flooding in an earthquake.

Earlier this year Hydro finalized the purchase of all but one of the 11 homes in the tiny Vancouver Islandcommunity of Jordan River. Thosehomeswere in the path of flooding from a potential dam break, and are expected to be removed.

For the residents downstream of the John Hart and Strathcona dams, BC Hydro estimates it will be 20 years before both dams are fully upgraded to withstand a one-in-10,000-year earthquake.

"We have a good plan," Watson said."Until then, there is this interim risk."

To hear the full story, click the audio labelled:The seismic risk from Campbell River's dams